Siglets.com
Free Signature files for email. Includes ASCII pictures, HTML and quotations.

Signatures, Smileys & Acronyms
Links to information on email signatures, smileys and acronyms, from your About.com Guide.

Whistle Stop Cafe
Personal forum with cooking tips, recipes, and simple signatures. Signature requests are welcome.

Subject: Funny Email Sigs
One line signatures captured from the Internet.

My Favorite Signature Quotes
Collection of signatures and quotes to be used in email signature files.

SigMania
Members-only Yahoo group for making signatures. Willingness to share is a must here: signatures, email signatures, tags.

Making Your Mark
Expressing yourself through someone elses words is just one way of making a signature file. From About.com.

The Gallery of Annoying Email Signatures
Signatures that are annoying and provide no useful information.

A Guide to Email Signatures
An article on creating sensible and professional looking email signatures.